As a conventional air-conditioning apparatus which performs heat exchange between a refrigerant and a heat medium, such as water, a cooling apparatus (see, for example, Patent Literature 1) which detects the temperature of a low-pressure liquid refrigerant that flows into an evaporator (intermediate heat exchanger) and the inflow temperature of cooled fluid (heat medium) and determines whether the cooled fluid is frozen or not has been available. In such a cooling apparatus, when a determining unit determines “presence or absence of freezing” or “possibility of freezing,” a controller controls a compressor, an air-sending device, expansion means, and a pump. In the case of occurrence of freezing, the controller issues an alarm.
Further, an air-conditioning apparatus which includes a first bypass pipe for allowing bypassing of a refrigerant inflow part and a refrigerant outflow part of a floor cooling and heating heat exchanger (intermediate heat exchanger), and flow rate control means provided at the first bypass pipe, has been available. In the case where the temperature of a low-temperature refrigerant becomes 0 [degrees Centigrade] or below, the air-conditioning apparatus allows bypassing of the floor cooling and heating heat exchanger (see, for example, Patent Literature 2).
Furthermore, an air-conditioning apparatus which includes an outdoor heat exchanger (intermediate heat exchanger) for exchanging heat between refrigerant and circulation water as heat source water which is supplied from outside, and a bypass pipe for causing refrigerant to bypass, without passing through the outdoor heat exchanger, an auxiliary heat exchanger (see, for example, Patent Literature 3), has been available. The air-conditioning apparatus, in the case where the temperature of a heat source is low, causes refrigerant to bypass the outdoor heat exchanger, thereby preventing the refrigerant from freezing.